The connection of communication systems to the public network via SIP Trunking can be used instead of or in addition to traditional PSTN trunks. Many VoIP Providers, also known as ITSPs, are offering corresponding services. The following article gives an overview of the SIP trunking features and limitations and lists the Providers, which have been tested and released with the SME platform OpenScape Business.

Overview

OpenScape Business has been tested with a large number of Internet telephony providers that support SIP. Continuously new providers are tested, released and included within administration. As the SIP recommendations leave some room for interpretation, there are differences in the range of features supported with a specific provider. In this chapter general information is given which is valid for all SIP Providers.

SIP trunking features

SIP trunking with single numbers (MSN) and up to 30 SIP user accounts (called Internet telephony stations in WBM)

SIP trunking with Direct Inward Dialing (DID)

Comprehensive feature set available e.g.

CLIP

Hold, Consultation, Toggle

Transfer (attended, semi-attended)

Ringing group, Call pickup

Conference

Call Forwarding

Call deflection (new in V2R4)

DTMF transmission e.g. for voicemail access

Location information for emergency calls

Simultaneous VoIP connections depending on available DSL bandwidth, used Codec and system.

Automatic fallback at SIP trunk failure

Voice Codecs G.711 and G.729

Fax over IP via T.38

Security Warning - Malicious attacks from the Internet may lead to reduced service quality or toll fraud! Please strictly follow these basic rules:

Never open up the firewall in an internal or external router e.g. by forwarding port 5060. The SME platforms take care of opening the firewall for traffic with the selected VoIP providers. Attacks from other internet addresses are therefore blocked. Opening up the router's firewall would invalidate this security measure.

Special call numbers (e.g. 0800, 0900, 0137) are not supported by all SIP providers

analog fax/modem connections are not supported by all SIP providers.

Emergency call numbers (e.g. 110, 112) are not supported by all providers.

How to get a new VoIP provider released

Tests are necessary with every new provider before making installations in the field due to different implementations of the SIP protocol. Otherwise no support is available for an ITSP. Test resources have to be provided by the region or partner.

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Select the VOIP / SIP trunking providers, which are most important for your business, estimate business relevance and get agreement for start of certification from product management.

After successful tests the VoIP provider will be released and published on this page. Regular back level support is available for issues with the new provider after that. A preconfigured VoIP provider profile will be included in the OpenScape Business administration for easy setup.
Certified providers are entitled to label their SIP Trunking Service with the OpenScape Business certified ITSP emblem

Tested VoIP Providers by Countries

The main SIP trunking functions of the SME platforms have been tested with the following Internet telephony providers. For detailed information see the document Overview about Released SIP Providers below.

Released SIP Providers in Detail

The table above shows the ITSPs that passed successfully a connectivity test. More details about test results, supported features and restrictions for a specific ITSP are listed in following PDF document.